WASHINGTON
— No one stands still very long in the basement offices of the Senate Permanent Subcommittee on Investigations  it's too easy to be trapped against a wall by incoming boxes of documents tied to the collapse of Enron Corp.

For a time, the subpoenaed documents were pouring in at the rate of dozens of boxes a day. New storage rooms were commandeered in the building next door to stack the overflow. The copy machine gave out and was hauled away.

The calendar may suggest that the 107th Congress is winding down, but many of its investigating committees are just warming up for what is becoming the most extensive investigation Congress has ever conducted into the affairs of corporate America.

Nearly a dozen committees are engaged in this investigation. On Tuesday, the House Energy and Commerce Committee requested more documents from lifestyle guru Martha Stewart on possibly illegal trades of a stock she owned.

But among the congressional panels, the one in this Senate basement has a character all its own. None of its members seem worried about being first to the television lights. There are no rancorous turf wars with colleagues on other committees. As remarkably, the chairman of the subcommittee on investigations, Carl Levin (D) of Michigan, and the ranking GOP member, Susan Collins of Maine, are on the same page on this investigation. So is the staff of six who work on this issue, sharing documents and late-night Diet Cokes and interviewing witnesses together.

"One thing that makes this committee different is that it is very much of a bipartisan effort. There is no bickering going on. They aren't out to put a notch in their belt or play politics," says Lynn Turner, director of the Center for Quality Financial Reporting at Colorado State University and a former chief accountant at the Securities and Exchange Commission.

"In terms of really getting in and exposing problems, I have not seen anyone do as thorough or as good a job as [Senator] Levin does," adds Mr. Turner, who has testified before several congressional panels regarding corporate misdeeds.

While other committees zoom in on the top "bad apples" at companies like the Enron Corp. and WorldCom, Senators Levin and Collins are probing how deeply corruption has spread to include the investment banks that helped structure the "sham prepays" and other deals to hide billions in corporate debt, and the accountants, lawyers, and analysts who helped such deals along. Probes of more corporations could follow.

"The depth of what I would consider to be accounting practices either marginal or deceptive is much greater than I expected," says Levin in an interview in his office. "Nothing shocks me any more."

After probing the role of Enron's board of directors in the energy-trading firm's collapse, the committee moved on to the rule of financial institutions, like CitiGroup, J.P. Morgan Chase, and Merrill Lynch. Next, the committee plans to delve into the way so-called special-purpose and offshore entities are used for tax avoidance or to hide the real nature of transactions. Before end of session, it may also call in some of the lawyers close to these corporate scandals.

THE committee's history of solid bipartisan work has made it one of the most respected panels in the Congress, despite serving as venue in the 1950s for Sen. Joseph McCarthy's inquisition into communists in government. (Robert Kennedy's picture hangs on the wall, and the desk he used as chief counsel for the McCarthy panel is still elbow-deep in the papers of the panel's current counsel and chief investigator.)

But the bruising, badger-the-witness style of the McCarthy days couldn't be farther from the nose-to-the-documents style of the panel today.

The committee is now the Democratic leadership's go-to group for the most complex, detailed issues in the Senate. Its three-year, six-volume investigation into the use of private and correspondent banks for money laundering became part of the counterterrorism law enacted last October.

A talented legislator and master of complex issues, Levin is an owlish cross between Lieutenant Columbo and just-the-facts-ma'am Joe Friday. The battered briefcase he takes home after even late nights in the office is not a prop. He reads these documents, but he won't say where: "My wife would kill me."

"Documents are extremely powerful objects, I learned early in my life as a lawyer how important an exhibit is and how you've really got to know them. If you flub one, it can create a credibility issue about everything else you're doing."

The panel's ranking Republican is also no slouch as an investigator. Susan Collins came to the Senate straight out of college as an intern for Sen. William Cohen (R) of Maine, then served as a staff director for a panel of the Senate Governmental Affairs Committee, where she earned the respect of many in the small, tight world of top staff investigators on Capitol Hill.

Now, the challenge is to get to the top of the document pile. More than 1 million pages are indexed, as they come in, by a handful of people including a few volunteers rotating in on loan from other agencies in government. The most interesting documents are flagged with colored Post-it notes for later analysis.

If a puzzling question pops up  such as the one about why an investment bank like Merrill Lynch had bought three barges in Nigeria  committee staff run down the answers in other documents and interviews. Only after all the dots are connected will the committee take the questions to hearing rooms and panels of witnesses.

An intern describes the long days that become nights, then days again, as "a show that never ends."

Since many of the corporate witnesses called before these investigating panels also face possible criminal prosecution, many are refusing to testify. "Without witnesses, the exhibits have to speak for themselves," says Levin.

Still, with 700 boxes to be perused and more on the way, Levin says his main job is "looking for space" to put them.